(1) Field of the Invention
This invention relates to a novel water dispersible cold rolling oil composition for aluminum and aluminum-containing alloys (hereinafter referred to simply as "a cold rolling oil for aluminum") and, more particularly, to a cold rolling oil for aluminum comprising (a) lube oil components and (b) a water soluble cationic polymer compound or a water soluble amphoteric polymer compound.
(2) Description of the Prior Art
A thin plate of metal is conventionally produced by means of a hot or cold rolling operation, in which various lube oils are employed depending on the manner of the rolling operation and the kind of metal to be rolled.
The characteristics required for such rolling lube oils include; having an excellent rolling lubricity, being capable of removing the working heat, not generating stains during annealing due to oil residues on the surface of the metal sheet, an aqueous fluid of the lube oil being easily controlled, having an extended life of use, being economical, and not generating rust on the metal surface.
Taking the cold rolling operation of steel as an example, the lubrication is conventionally performed by a lube oil composition emulsified in water and containing, as a base oil, an animal or vegetable oil such as tallow oil and palm oil, or a mineral oil, and oiliness improvers such as a fatty acid and the like.
On the other hand, the cold rolling of aluminum and aluminum-containing alloys is lubricated by a lube oil composition as they are, without being emulsified in water, said lube oil components comprising a low viscosity mineral oil, as a base oil, and various oiliness improvers.
The reason for using mineral oil having a low viscosity is effecting the rolling operation in the lubricating boundary area where the roll and an aluminum sheet contact each other through some molecular layers of a boundary lubricant film, thereby providing the plate surface with a luster which is inherent to aluminum.
The above-mentioned rolling lube oil for aluminum, however, has a low boiling point and thus is readily inflammable, because a low viscosity mineral oil is composed of hydrocarbons having a smaller molecular weight. Therefore, the measure is taken to obtain a low viscosity mineral oil with a higher flash point and a narrower boiling range (the fractionation range) by removing lower boiling components. Nevertheless, the rolling operation using such mineral oil involves the risk of fire all the time.
Furthermore, a tendency in recent years of the cold rolling operation of aluminum and aluminum-containing alloys is to use a higher speed and a higher reduction which has made the use of the conventional low viscosity mineral oil significantly handicapped because of incapability of mineral oils of removing the working heat.